Wireless Local Area Networks (WLANs) are being contemplated or are known. Voice services in WLANs are typically supported by WLAN servers that may be referred to as private branch exchanges (PBXs) or enterprise servers. The PBX normally provides a control and switching function for the WLAN and communication units operating therein or users thereof. The WLAN can be an attractive and inexpensive alternative for typical voice services such as telephony or dispatch services and may provide additional amenities such as high-speed wireless Internet and Intranet access as well as other real-time applications that may be more specific to a given enterprise.
Wireless wide area networks (wireless WANs or WANs), such as conventional cellular telephone systems, are also known. Such networks provide the advantage of wide area coverage but may not be economically attractive for routine access to wideband or high speed data capabilities, such as are required for certain Internet or Intranet applications. Nevertheless a communication unit that is operating on a WLAN may move beyond the effective service area for the WLAN and thus need support or services from a WAN. Similarly a communication unit that is operating in the WAN may enter the coverage area of a WLAN and want to transfer ongoing calls to the WLAN in order to use services available via the WLAN or avoid costs and the like for using the WAN. In situations, sometimes referred to as loosely coupled systems, where the WAN is indirectly coupled to the WLAN via the public switched telephone network (PSTN) or communication unit operating thereon this can present problems, such as whether to hand in a call or particularly multiple calls without unduly complicating the underlying systems or communication units or dropping calls or otherwise being an inconvenience to users.
Therefore, a need exists for methods and apparatus to facilitate handin of calls from one system to another for communication units operating within such coupled communication networks